The objective of the proposed research is to develop and study a new salivary gland and neuroeffector preparation from the basomatophoran snail Helisoma trivolvis. The relative simplicity of the system's morphology and innervation in conjunction with its amenability for intracellular microelectrode analysis suggests that it will provide a useful model for electrophysiological and ultrastructural analysis of the cellular processes underlying stimulation-secretion coupling. The initial step of our analysis will be to reassess and extend the current evidence favoring the existance of a monosynaptic connection between the salivary effector neuron and acinar gland cells. If the connection is monosynaptic, we will attempt to identify the neurotransmitter released by the effector neuron using pharmacological, neurochemical and ultrastructural criteria. The puntative transmitter substance(s) for this synapse will then be used to study the ionic bases of excitation-secretion coupling in acinar gland cells.